import numpy as np
import pandas as pd

s=pd.Series([i*2 for i in range(1,11)])
dates=pd.date_range('20170301',periods=8)
df=pd.DataFrame(np.random.randn(8,5),index=dates,columns=list('ABCDE'))
df1=df.reindex(index=dates[:4],columns=list('ABCD')+['G'])
df1.loc[dates[0]:dates[1],'G']=1
print(df1)
print(df1.dropna())
print(df1.fillna(value=1))
